1. Field of the Invention
The present invention relates to a toner and a developer.
2. Description of the Related Art
In recent years, a toner is required to have a small particle diameter for achieving a high-quality output image, high temperature-resistant offset property, low-temperature fixing property for energy conservation, and heat-resistant storage stability for enduring high-temperature and high-humidity conditions during storage or transportation after manufacturing. In particular, improvement of low-temperature fixing property is extremely important since power consumption during fixing consumes a lot of power in an image formation process.
Conventionally, a toner manufactured by a kneading pulverization method has been used. The toner manufactured by a kneading pulverization method has problems such as insufficient quality of an output image and high fixing energy because it is difficult to reduce its particle diameter, its shape is non-uniform, and its particle diameter distribution is broad. Also, when a wax (releasing agent) is added for improving fixability, the toner manufactured by a kneading pulverization method cracks at an interface of the wax during pulverization, and the wax is present in abundance at a surface of the toner. Thus, while it provides a releasing effect, adhesion of the toner to a carrier, a photoconductor and a blade (filming) is more likely to occur, and there is a problem that overall performance is not satisfactory.
Therefore, in order to overcome the above problems of the kneading pulverization method, a method for manufacturing a toner by a polymerization method is proposed. For a toner manufactured by a polymerization method, reduction of particle diameter is easy, and the toner has a sharp particle size distribution compared to a particle size distribution of the toner manufactured by a pulverization method. Further, encapsulation of a releasing agent is possible. As a method for manufacturing a toner by a polymerization method, for the purpose of improving low-temperature fixing property and improving high temperature-resistant offset property, a method for manufacturing a toner from an elongation reaction product of a urethane-modified polyester as a toner binder is proposed (for example, see Japanese Patent Application Laid-Open (JP-A) No. 11-133665).
Also, a method for manufacturing a toner which has superior powder flowability and transfer property with a reduced particle diameter as well as superior heat-resistant storage stability, low-temperature fixing property and high temperature-resistant offset property is proposed (for example, see JP-A Nos. 2002-287400 and 2002-351143).
Also, a method for manufacturing a toner including an aging step for manufacturing a toner binder having a stable molecular weight distribution and achieving both low-temperature fixing property and high temperature-resistant offset property is proposed (for example, Japanese Patent (JP-B) No. 2579150 and JP-A No. 2001-158819).
However, these proposed methods do not satisfy a high level of low-temperature fixing property required in recent years.
Thus, for the purpose of obtaining a high level of low-temperature fixing property, a toner which includes: a resin including a crystalline polyester resin; and a releasing agent and which has a sea-island phase separation structure due to the resin and a wax mutually incompatible is proposed (for example, JP-A No. 08-176310).
Also, a toner including a crystalline polyester resin, a releasing agent and a graft polymer is proposed (for example, JP-A No. 2005-15589).
With these proposed technologies, low-temperature fixing may be achieved because a crystalline polyester resin rapidly melts compared to a non-crystalline polyester resin. However, even when the crystalline polyester resin corresponding to an island in the sea-island phase separation structure, the non-crystalline polyester resin corresponding to a sea as a major portion does not still melt. Then, fixing does not occur until both the crystalline polyester resin and the non-crystalline polyester resin melt to some degree, and these proposed technologies do not satisfy a high level of low-temperature fixing property demanded further in recent years.
Accordingly, a toner causing no filming and having superior low-temperature fixing property, high temperature-resistant offset property and heat-resistant storage stability is desired at present.